Soldering iron



F. KUHN ET AL.

SOLDERING IRON July 25, 1939.

Filed Nov. 16, 1936 /N VENIORS m N M R oww H T T N A HE U Km KE Nm MAW trl- o NGE i m u Patented July 25, 1939 UNITED STATES PATENT OFFICE Birmingham, Mich.,

assignora to American Electrical Heater Company, Detroit, Mich., a corporation of Michigan Application November 16, 1936, Serial No. 111,163

2 Claims.

The invention relates to electrically heated tools and more particularly to electrically heated soldering irons designed for more or less constant use and for fine work, such as connections f radio apparatus. It is one of the objects of the invention to obtain a construction in which the heat generation is located in close proximity to the point of application. It is a further object to reduce the consumption of electrical energy to the minimum and to obtain a high degree of eiiioiency. Still further, it is an object to obtain a construction in which the operating point together with the electrical heating unit therefor forms a detachable unit which, in case that it becomes inoperative, may be quickly replaced by a similar unit. With these objects in View, the invention consists in the construction as hereinafter set forth.

In the drawing:

Figure 1 is a longitudinal section partly in elevation through my improved tool;

Figure 2 is an enlarged longitudinal section through the point and a portion of the handle shank to which it is connected;

Figures 3 and 4 are views similar to Figures l and 2 showing a modied construction;

Figure 5 is an elevation of the detachable or replaceable unit.

As illustrated, A is a suitable handle member 3U preferably having the hollow wooden portion B and the tubular metallic shank C. The latter is attached to the portion B by means of an eX- ternally threaded head C engaging an internally threaded metallic bushing C2 in the hollow member B. The outer end of the shank C is slitted to form a clamp and is provided externally with a tapering thread for engagement with the correspondingly tapering internal thread in a collar member D. E is the point member which is 1., formed with an integral hollow shank E adapted to be secured to the shank member C by the clamping collar D.

F is the electrical heating unit which as shown in Figure 2 comprises a resistor coil F' wound .i5 about an insulator tubular core member F2 formed of suitable material, such as porcelain. The inner end of the coil has a portion extending through a longitudinal passage in the insulator tube G within the shank member C and the oppo- 50 site end of the coil is return-bent and has an extension passing axially through the tubular core F2 and then through a parallel passage in the insulator tube G. These conductors are then connected with terminals H and H which are 55 mounted on a suitable support H2 secured to the head C' and located within the hollow wooden handle B. These terminals H and H are respectively connected with conductors I and I of a ilexible insulated cord which passes from the end ci the handle to the source of electrical energy.

The coil F detachably engages the hollow shank E and is insulated therefrom by suitable means, such as a winding of mica J therebetween. This coil is designed for use with low voltage current, such as from 6 to 20 Volts and is, therefore, of a substantial cross section and of a length limited so that it may be stored within the length of 'the shank E. The resistance of the coil is so proportioned that with the low voltage current it will generate just sufficient heat to maintain the point at operative temperature during constant use. If, however, the tool is used only intermittently the amount of current Consumption is so small that the expense is negligible.

With the modified construction shown in Figures 3 to 5, instead of mounting the coil upon the handle member with a detachable engagement between the same and thepoint member, the coil and the point form a single unit which may be detachably engaged with the handle member and so as to form electrical connection between the coil and the current supply conductors. Such construction has the advantage that if at any time the coil should burn out it is only necessary for the operator to detach the unit and replace it by another unit which is instantaneously ready for operation.

For simplicity in construction, we preferably form this unit with one grounded terminal which on account of the low voltage may be used without danger of shock to the operator. As illustrated, K is a metallic rod which forms a core around which is wound a resistor coil L. The convolutions of this coil are slightly spaced from the core and are insulated therefrom by suitable means, such as a layer of mica M or a plastic insulator cement. The point N has a tubular shank N which is clamped to the handle by the collar D, as previously described. Within this shank is placed the core member K and coil L with an insulating plastic cement for holding the convolutions of the coil from electrical contact with the shank. However, one end of the coil is directly grounded on the shank as indicated at O while the opposite end is connected as indicated at P to the lower end of the rod or core member K. The rod K projects beyond the hollow shank N in the handle shank C and its upper end is adapted for electrical connection with a conductor socket Q. This socket is mounted in an insulator bushing R within the shank member C, which socket is connected by a conductor S to an insulated terminal member T Within the handle A. A second terminal member T is grounded upon the tubular shank C as through the medium of metallic members T2 and T3 so as to form electrical connection therethrough with the grounded terminal O on the point shank N.

The construction above described forms a simple unit which may be manufactured at such low cost that the user may afford to throw it away and replace it by a similar unit whenever 'this is necessary. To perform this replacement it is merely necessary to. loosen the clamp or collar D; withdraw the unit; replace it with another unit, and again fasten the clamp.

What we claim as our invention is:

1. In a relatively low wattage electrically heated soldering iron, the combination of a handle member provided with an electrical service connection, and inner and outer concentric sockets forming the terminals thereof, a replaceable unit detachably engaging said handle comprising a soldering point having an integral hollow shank, a resistor coil within said shank having one end grounded thereon, the convolutions of said coil being insulated from the shank, a conductor core member within said coil and insulated from the convolutions thereof being connected to the opposite terminal of the coil and projecting outward beyond said hollow shank, said core member and hollow shank forming the contacts for connection respectively with said inner and outer sockets of said electrical service connection upon engagement of said unit with said handle.

2. A relatively low wattage electrically heated soldering iron comprising a hollow handle member provided with an electrical service connection, a metallic tube secured within and projecting outward from said hollow handle member being connected to one terminal of said electrical service connection, an insulator bushing within said tube, a socket within said bushing connected to the other terminal of said electrical connection, a replaceable unit detachably engaging said handle member comprising a soldering point having an integral hollow shank, a resistor coil within said shank having one end grounded thereon the convolutions of said coil being insulated from said shank, a conductor core member within said coil and insulated from the convolutions thereof being connected with the opposite terminal of the coil and projecting beyond said hollow shank, said core member and hollow shank respectively engaging said socket member and tube to establish electrical connections to said coil, and clamping means for securing said hollow shank to said tube.

FRANK KUHN. 4 LAURENCE H. THOMAS. 

